1. Field of the Invention
The present invention relates to a solid-state image pickup device which renders the tip inserting portion of an electronic endoscope bendable in an arbitrary direction and which can be used commonly in various types of electronic endoscopes.
2. Description of the Related Art
In general, endoscopes used for medical and industrial purposes incorporate a solid-state image pickup device at the tip of an inserting portion. The inserting portion assumes a variety of shapes depending on the use of an endoscope. For example, the length and the diameter of the inserting portion subdivide in ranges of 0.5-30 m and 4-12 mm, respectively. The inserting portion is further classified into types having view-range-related functions such as a direct view function and an oblique view function, a type in which the tip of the inserting portion is bendable, and other types. Therefore, the configurations of solid-state image pickup devices incorporated in such endoscopes need to be designed for the respective types of inserting portions.
Japanese Examined Patent Publication No. Hei. 3-71688 and Japanese Unexamined Patent Publication No. Sho. 60-208726 disclose typical solid-state image pickup devices used at the tip of an inserting portion of conventional electronic endoscopes, which devices will be described below in detail.
FIG. 11 schematically shows an example of a conventional solid-state image pickup device. In FIG. 11, reference numeral 100 denotes a solid-state image pickup element chip; 101, a receptacle; 102, a metal thin wire; 103, an optical glass plate; 104, a lead terminal; 105, solder; 106, a circuit board; 107, an electronic part; and 108, a signal line.
In this solid-state image pickup device, the circuit board 106 is provided adjacent to the back surface of the receptacle 101 so as to extend approximately perpendicularly to the latter. The top and bottom lead terminals 104 extending from the receptacle 101 are bent inward and bonded, with the solder 105, to electrode pads (not shown) of the circuit board 106 on which the electronic parts 107 are mounted. The signal lines 108 are bonded, with the solder 105, to electrode pads (not shown) that are provided on a rear end portion of the circuit board 106. The solid-state image pickup element chip 100 is die-bonded to the receptacle 101, and the metal thin wires 102 are wire-bonded to electrode pads (not shown) that are formed on the respective surfaces of the solid-state image pickup element chip 100 and the receptacle 101. The electrode pads of the receptacle 101 are connected to the lead terminals 104 via an internal wiring pattern (not shown) formed on an inside layer of the receptacle 101. The receptacle 101 is hermetically sealed with the optical glass plate 103.
The structure of the above solid-state image pickup device is suitable for use in an inserting portion of an endoscope which is small in diameter and is not required to be bendable. This is because where the circuit board 106 needs to accommodate a large-scale circuit, the electronic parts mounting area can be increased by increasing the length of the circuit board 106 rather than its width. However, the above structure is not suitable for use in an inserting portion that is required to have a shallow tip as well as to be bendable.
FIG. 12 shows another example of a conventional solid-state image pickup device. In this device, in contrast to the case of FIG. 11, a circuit board 109 mounted with electronic parts 110 is provided adjacent to the back surface of a receptacle 101 in parallel therewith. The circuit board 109 has through-holes (not shown) at positions opposed to lead terminals 104. The lead terminals 104 are inserted through the through-holes (not shown) and bonded thereto with solder 105. To make the inserting portion small in diameter, the outer size of the circuit board 106 is set the same as or smaller than that of the receptacle 101. Since the structure in the neighborhood of the solid-state image pickup element chip 100 is the same as that shown in FIG. 11, it is not described here.
The solid-state image pickup device of FIG. 12 is suitable for use in an inserting portion which is required to be bendable, because it allows the tip of the inserting portion to be made short. However, in contrast to the case of FIG. 11, the degree of freedom of circuit designing is low, because the outer size of the circuit board 109 is limited by that of the tip of the inserting portion of an endoscope.
As described above, in the conventional solid-state image pickup devices, the configuration is designed individually in accordance with the functions/properties or the size required for each endoscope. Therefore, they cannot be used commonly in a variety of endoscope inserting portions, and developing a solid-state image pickup device each time for each particular use takes long time.
The present invention has been made to solve the above-described problems in the art, and has an object of providing a solid-state image pickup device which makes the tip of an inserting portion small and does not lower the bendability of the inserting portion, and which can be used commonly in a variety of endoscopes.
To attain the above object, according to the invention, there is provided a solid-state image pickup device in which first and second electrode pad groups that are electrically connected to each other are formed on a circuit board, which extends approximately perpendicularly to the back surface of a solid-state image pickup element chip, with a gap that allows the circuit board to be separated in the width direction by cutting.
With the above configuration, the invention provides an advantage that the solid-state image pickup device can accommodate at least two types of endoscopes. That is, the circuit board is used as it is, i.e., without cutting it for use in an endoscope that is not required to be bendable. For use in an endoscope that is required to be bendable, the circuit board of a completed solid-state image pickup device is cut and the separated pieces of the circuit board are connected to each other by a separately provided connection member and thereby kept away from each other when used.
Further, the separation and elongation of the circuit board can be conducted either in a manufacturer of a solid-state image pickup device or in a manufacturer of an endoscope. Thus, the manufacturer of an endoscope can determine, on its own, the length of an elongated circuit board and the structure for incorporating an image pickup device in the inserting portion of an endoscope.